The "early out" feature in CreateDirRecursively was first added in 3193 (with return value == failed) and amended in 3206 (with correct return value).
What "early out" does is abort if the requested directory already exists, instead of checking the root directory and then hangling through the entire FS hierarchy until failing in the very end.
The "early out" code is nothing but:
if(wxDirExists(full_path)) // early out
return true;
So, in other words, "early out" does what you should have done in wiz.cpp in the first place. No special magic happens. If the path exists, then the function returns immediately (success). If it does not exist, the function attempts to create it in the same way it has been doing for years (success if the folder can be created, failure otherwise).
By the way,
CreateDirRecursively has a
wxLogNull object, so I don't see how this function could produce a "could not create directory" warning, as these are discarded.